The 1/20 Wave Tech Spec optical flat mirrors are manufactured using optical fused silica for extra thermal stability and are available coated or uncoated. These mirrors are designed for demanding imaging systems, laser applications, holography, optical path folding, and as reflectors for autocollimating requirements. The primary surface is precision ground and polished to the stated accuracy and certified by a Zygo GPI-XP interferometer. The secondary surface is pitch polished to window quality.